bit manipulation in C#

can someone please explain why one needs a larger data type for the result variable in C# as in the code below

Code:

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using System;

class MyClass {

        public static void Main() {
        byte varA=10;// binary equivalent for 10 is 00001010
        byte varB=20;// binary equivalent for 20 is 00010100
        int result=varA & varB; // AND operation result should be 00000000
  }

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the result of any logical operation never results in a larger number, why the need for one? i tried to compile using result as byte and got "Cannot implicitly convert type 'int' to 'byte'" error.


luigi

An int is 4bytes, while your byte is only, well, a byte? I think your trying to store too little information in the "result" variable. Try changing result from type "int" to type "byte" and see if it works.

Someone correct me if I'm wrong on the above logic.

I believe he said he'd tried with Byte but had to use an int?

Could just be something funny with the & operator. Division of one int against another int rsults in an int by default when sometimes you want a double etc, this may be the opposite case. If you know this to be safe, you should be able to do this:

byte result = (byte)(varA & varB);

Although the extra casting can have a performance penalty.

Quote:

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Originally Posted by stovellp

I believe he said he'd tried with Byte but had to use an int?

Could just be something funny with the & operator. Division of one int against another int rsults in an int by default when sometimes you want a double etc, this may be the opposite case. If you know this to be safe, you should be able to do this:

byte result = (byte)(varA & varB);

Although the extra casting can have a performance penalty.

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Oh sorry, I had read that wrong; stupid me. :(

thanks for your replies guys, i have experimented in debug mode with numbers less than 255 and always get the correct result using ints so im going to use ints, i think ints are the default data types in .NET


luigi